Liquid crystal display device, instrument panel, automotive vehicle, and liquid crystal display method

• US 20090251299A1
• Filed: 05/29/2006
• Published: 10/08/2009
• Est. Priority Date: 09/27/2005
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Mizumaki, Hidetaka, Wakita, Yasuhiro
• Granted Patent: US 8,339,345 B2
• Time in Patent Office: Days
• US Class Current: 340/425.500
• CPC Class Codes: G02F 2203/30 Gray scale
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2340/0428 Gradation resolution change
• CPC Class Codes: G09G 2340/16 Determination of a pixel data signal depending on the signal applied in the previous frame
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

In one embodiment of the present invention, a liquid crystal display device is provided with a gray scale conversion section which converts a gray scale conveyed by an input video signal into a gray scale value of a high gray scale region, and then outputs it to the liquid crystal drive device if the gray scale value of the input video signal is of a low gray scale region.

Claims

1. A liquid crystal display device including a liquid crystal drive device for operating liquid crystal according to an input video signal inputted in the liquid crystal display device, comprising:

a gray scale conversion means, which, if the input video signal conveying a gray scale value belonging to a low gray scale region, converts the gray scale value of the input video signal to a gray scale value belonging to a high gray scale region, and outputs the video signal having the converted gray scale value to the liquid crystal drive device,

where the low gray scale region is one of two regions into which a range of possible gray scale values are divided and to which gray scale values that cause the liquid crystal display device to display at low luminance are belonged, and the high gray scale region is the other one of the two regions to which gray scale values that cause the display device to display at high luminance are belonged.

2. The liquid crystal display device as set forth in claim 1 wherein the gray scale conversion means performs a conversion with a conversion table in which the gray scale values are associated to values to which they will be converted.

3. The liquid crystal display device as set forth in claim 1, wherein the gray scale conversion means compares a threshold with the gray scale value conveyed by the input video signal, the threshold dividing the low gray scale region from the high gray scale region;

and

perform the conversion if the gray scale value is less than or equal to the threshold or if the gray scale value is less than the threshold.

4. The liquid crystal display device as set forth in claim 1, wherein the gray scale conversion means judges whether A numbers of bit values from a most significant bit of the gray scale value conveyed by the input video signal are all 0 or not, where the A number is a number of sequential bits of bit value of 0 from the most significant bit in an bit expression of a threshold gray scale value dividing the low gray scale region and high gray scale region, and A number is a positive natural number.

5. The liquid crystal display device as set forth in claim 1 wherein the gray scale conversion means performs the conversion in such a manner that the gray scale value of the input video signal is converted into a gray scale value near a minimum gray scale value of the high gray scale region if the video signal conveying the gray scale value of the low gray scale region is inputted.

6. The liquid crystal display device as set forth in claim 1 wherein the gray scale conversion means shifts a threshold according to an ambient temperature of the liquid crystal display device, the threshold dividing the low gray scale region from the high gray scale region.

7. The liquid crystal display device as set forth in claim 1 wherein the gray scale conversion means shifts a threshold according to a surface temperature of the liquid crystal display device, the threshold dividing the low gray scale region from the high gray scale region.

8. The liquid crystal display device of claim 6, comprising:

a temperature sensor for measuring the temperature, and outputting a digital video output.

9. The liquid crystal display device as set forth in claim 1 wherein the gray scale conversion means shifts a threshold according to a time elapsed after power is applied to the liquid crystal display device, the threshold dividing the low gray scale region from the high gray scale region.

10. The liquid crystal display device as set forth in claim 9, comprising:

a timer for measuring the time elapsed after the power is applied to the liquid crystal display device, the timer counting a vertical synchronization-timing signal of the liquid display device.

11. The liquid crystal display device as set forth in claim 1 wherein the gray scale conversion means narrows a range of gray scale values possible to output to the liquid crystal drive device.

12. The liquid crystal display device as set forth in claim 1 wherein the gray scale conversion means decreases a contrast ratio.

13. The liquid crystal display device as set forth in claim 1, comprising:

a light source brightness adjustment means for adjusting brightness of a light source of the liquid crystal display device according to the gray scale value of the input video signal.

15. An instrumental panel comprising a liquid crystal display device as set forth in claim 1.

16. An automobile vehicle comprising an instrumental panel as set forth in claim 15.

14. A liquid crystal display device including a liquid crystal drive device for operating liquid crystal according to an input video signal inputted in the liquid crystal display device, comprising:

a gray scale conversion means for decreasing a ratio of a maximum gray scale value to a minimum gray scale value displayable on the liquid crystal display device.

17. A means for operating liquid crystal of a liquid crystal display device including a liquid crystal drive device for operating the liquid crystal according to an input video signal inputted in the liquid crystal display device, the means comprising the steps of:

converting a gray scale value conveyed by the input video signal into a value of a high gray scale region when the gray scale value conveyed by the input video signal is of a low gray scale region; and

if the input video signal conveying a gray scale value belonging to the low gray scale region, converting the gray scale value of the input video signal to the gray scale value belonging to the high gray scale region, where the low gray scale region is one of two regions into which a range of possible gray scale values are divided and to which gray scale values that cause the liquid crystal display device to display at low luminance are belonged, and the high gray scale region is the other one of the two regions to which gray scale values that cause the display device to display at high luminance are belonged; and

outputting the video signal conveying the converted gray scale value to the liquid crystal driving device.